What does offsides mean in soccer?

Offsides in soccer means that the opponent is behind the defence. The player/opponent is between the sweeper and the goalie, which is illegal. The offensive team always has to be in front of the last player on the opposing team. If offsides was allowed, people could just cherry pick and stand by the goalie all game.

Offsides means that an offensive player is:
1. On their opponent's side of the field
2. Is nearer to the goal than any other defensive player (besides the goalkeeper)
3. AND a ball has been played to that player by a teammate

In soccer, players are restricted to their own half of the playing field. If they cross over the center line, a penalty may be assessed if they: touch the ball, interfere with an opponent, or gain an advantage by crossing the line. The penalty for an offside offense is a penalty kick awarded to the opposing team.

Offsides is when a member of the offense is behind every defensive player on the other team before the ball gets there. They must be on the opponent's side of the field, you can't be offsides on your side. It prevents people from hanging out by the goal all game.